Sea Surface Height and geostrophic currents during the DIAPICNA cruise.

<p>Station locations (open circles) overlaid on AVISO altimetry-derived geostrophic currents centered between 26/07/2011 and 01/08/2011, with color scale indicating the Sea Surface Height (SSH) in m.</p

Distribution of Carbon fixation and Organic Carbon in <3 μm and >3 μm large particles.

<p>(A) C-fixation rates (μmol m^-3 d^-1), and (B) longitudinal cross-sections of POC (μmol L^-1) depending on the particle size fraction (left: <3 μm; right: >3 μm). The Azores Front position is marked by a bold line.</p

Geochemical tracers of N₂-fixation along the DIAPICNA cruise transect.

<p>Longitudinal cross-sections of (A) nitrate concentration, (B) δ¹⁵N_NO3 signal, (C) PN isotopic signature and (D) Δ(15,18)—see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0150827#pone.0150827.e002" target="_blank">eq (2)</a>. The position of the Azores Front is indicated by a dashed line, and station i.d. is given on top.</p

Physical parameters monitored along the DIAPICNA cruise track.

<p>(A) Temperature (°C) longitudinal cross-section, with the position of the Azores Front deduced from the 16°C isotherm at 200m depth (dotted lines); (B) TS diagrams for stations A-E, with overlaid σ_θ density isolines. NACW: North Atlantic Central Water; 15MW: 15°C Mode Water; 18MW: 18°C Mode Water; SAIW: SubArctic Intermediate Water; MedW: Mediterranean Water; LSW: Labrador Sea Water. The black box indicates possible increased influence of Mediterranean Waters at 800–1000m in stations D and E.</p

Significant correlations between C-, N₂-fixations, UCYN abundance and physical-chemical conditions.

<p>Significant correlations between C-, N₂-fixations, UCYN abundance and physical-chemical conditions.</p